[google] Add new dump flag -pmu to display PMU data in dumps (issue6551072)

[tejohnson at google dot com (Teresa Johnson)]

Revised patch to add a new dump flag that dumps PMU profile information using
the -pmu dump option. (Was issue 6489092, creating new issue since I don't own
that one.)

Ok for google/main?

Passes bootstrap and regression tests.

Teresa

2012-09-24  Teresa Johnson  <tejohnson@google.com>
            Chris Manghane  <cmang@google.com>

	* doc/invoke.texi: Update -fpmu-profile-use option.
	* tree-dump.c: Add new dump flag.
	* tree-pretty-print.c (dump_load_latency_details): New function.
	(dump_pmu): Ditto.
	(dump_generic_node): Add support for new dump flag.
	* tree-pretty-print.h (dump_pmu): Declare.
	* tree-pass.h (enum tree_dump_index): Add new dump flag.
	* gcov.c (process_pmu_profile): Fix string table count assert.
	* opts.c (OPT_fpmu_profile_use_): Add support for -fpmu-profile-use.
	* gimple-pretty-print.c (dump_gimple_phi): Add support for new dump
        flag.
	(dump_gimple_stmt): Ditto.
	* coverage.c (struct pmu_entry): New structure.
        (struct gcov_pmu_summary): Ditto.
	(htab_pmu_entry_hash): New function.
	(htab_pmu_entry_eq): Ditto.
	(htab_pmu_entry_del): Ditto.
	(read_pmu_file): Ditto.
	(get_pmu_hash_entry): Ditto.
	(process_pmu_data): Ditto.
	(get_coverage_pmu_latency): Ditto.
	(get_coverage_pmu_branch_mispredict): Ditto.
	(pmu_data_present): Ditto.
	(coverage_init): Add pmu file read support.
	* coverage.h (get_coverage_pmu_latency): Declare.
        (get_coverage_pmu_branch_mispredict): Ditto.
	* common.opt: Update -fpmu-profile-use option.

Index: doc/invoke.texi
===================================================================
--- doc/invoke.texi	(revision 191138)
+++ doc/invoke.texi	(working copy)
@@ -399,7 +399,7 @@ Objective-C and Objective-C++ Dialects}.
 -fprofile-generate=@var{path} -fprofile-generate-sampling @gol
 -fprofile-use -fprofile-use=@var{path} -fprofile-values @gol
 -fpmu-profile-generate=@var{pmuoption} @gol
--fpmu-profile-use=@var{pmuoption} @gol
+-fpmu-profile-use=@var{pmudata} @gol
 -freciprocal-math -free -fregmove -frename-registers -freorder-blocks @gol
 -frecord-gcc-switches-in-elf@gol
 -freorder-blocks-and-partition -freorder-functions @gol
@@ -8381,12 +8381,11 @@ displayed using coverage tool gcov. The params var
 "pmu_profile_n_addresses" can be used to restrict PMU data collection
 to only this many addresses.
 
-@item -fpmu-profile-use=@var{pmuoption}
+@item -fpmu-profile-use=@var{pmudata}
 @opindex fpmu-profile-use
 
-Enable performance monitoring unit (PMU) profiling based
-optimizations.  Currently only @var{load-latency} and
-@var{branch-mispredict} are supported.
+If @var{pmudata} is specified, GCC will read PMU data from @var{pmudata}. If
+unspecified, PMU data will be read from 'pmuprofile.gcda'.
 
 @item -fprofile-strip=@var{base_suffix}
 @opindex fprofile-strip
Index: tree-dump.c
===================================================================
--- tree-dump.c	(revision 191138)
+++ tree-dump.c	(working copy)
@@ -824,9 +824,11 @@ static const struct dump_option_value_info dump_op
   {"nouid", TDF_NOUID},
   {"enumerate_locals", TDF_ENUMERATE_LOCALS},
   {"scev", TDF_SCEV},
+  {"pmu", TDF_PMU},
   {"all", ~(TDF_RAW | TDF_SLIM | TDF_LINENO | TDF_TREE | TDF_RTL | TDF_IPA
 	    | TDF_STMTADDR | TDF_GRAPH | TDF_DIAGNOSTIC | TDF_VERBOSE
-	    | TDF_RHS_ONLY | TDF_NOUID | TDF_ENUMERATE_LOCALS | TDF_SCEV)},
+	    | TDF_RHS_ONLY | TDF_NOUID | TDF_ENUMERATE_LOCALS | TDF_SCEV
+            | TDF_PMU)},
   {NULL, 0}
 };
 
Index: tree-pretty-print.c
===================================================================
--- tree-pretty-print.c	(revision 191138)
+++ tree-pretty-print.c	(working copy)
@@ -25,6 +25,9 @@ along with GCC; see the file COPYING3.  If not see
 #include "tm.h"
 #include "tree.h"
 #include "output.h"
+#include "basic-block.h"
+#include "gcov-io.h"
+#include "coverage.h"
 #include "tree-pretty-print.h"
 #include "hashtab.h"
 #include "tree-flow.h"
@@ -51,6 +54,7 @@ static void do_niy (pretty_printer *, const_tree);
 
 static pretty_printer buffer;
 static int initialized = 0;
+static char *file_prefix = NULL;
 
 /* Try to print something for an unknown tree code.  */
 
@@ -461,7 +465,32 @@ dump_omp_clauses (pretty_printer *buffer, tree cla
     }
 }
 
+/* Dump detailed information about pmu load latency events */
 
+static void
+dump_load_latency_details (pretty_printer *buffer, gcov_pmu_ll_info_t *ll_info)
+{
+  if (ll_info == NULL)
+    return;
+
+  pp_string (buffer, "\n[load latency contribution: ");
+  pp_scalar (buffer, "%.2f%%\n", ll_info->self / 100.f);
+  pp_string (buffer, "average cycle distribution:\n");
+  pp_scalar (buffer, "%.2f%% <= 10 cycles\n",
+             ll_info->lt_10 / 100.f);
+  pp_scalar (buffer, "%.2f%% <= 32 cycles\n",
+             ll_info->lt_32 / 100.f);
+  pp_scalar (buffer, "%.2f%% <= 64 cycles\n",
+             ll_info->lt_64 / 100.f);
+  pp_scalar (buffer, "%.2f%% <= 256 cycles\n",
+             ll_info->lt_256 / 100.f);
+  pp_scalar (buffer, "%.2f%% <= 1024 cycles\n",
+             ll_info->lt_1024 / 100.f);
+  pp_scalar (buffer, "%.2f%% > 1024 cycles\n",
+             ll_info->gt_1024 / 100.f);
+  pp_string (buffer, "] ");
+}
+
 /* Dump location LOC to BUFFER.  */
 
 static void
@@ -485,7 +514,51 @@ dump_location (pretty_printer *buffer, location_t
   pp_string (buffer, "] ");
 }
 
+/* Dump PMU info about LOC to BUFFER.  */
 
+void
+dump_pmu (pretty_printer *buffer, location_t loc)
+{
+  expanded_location xloc = expand_location (loc);
+  gcov_pmu_ll_info_t *ll_info;
+  gcov_pmu_brm_info_t *brm_info;
+  char *src;
+  uint64_t src_size;
+
+  if (!xloc.file)
+    return;
+
+  if (!file_prefix)
+    file_prefix = getpwd ();
+
+  if (!IS_ABSOLUTE_PATH (xloc.file))
+    {
+      src_size = strlen (xloc.file) + strlen (file_prefix) + 1;
+      src = XCNEWVEC (char, src_size + 1);
+      strcpy (src, file_prefix);
+      strcat (src, "/");
+      strcat (src, xloc.file);
+    }
+  else
+    src = xstrdup (xloc.file);
+
+  ll_info = get_coverage_pmu_latency (src, xloc.line);
+  brm_info =
+      get_coverage_pmu_branch_mispredict (src, xloc.line);
+
+  if (ll_info)
+    dump_load_latency_details (buffer, ll_info);
+
+  if (brm_info)
+    {
+      pp_string (buffer, "[branch misprediction contribution: ");
+      pp_scalar (buffer, "%.2f%%", brm_info->self / 100.f);
+      pp_string (buffer, "] ");
+    }
+
+  XDELETE (src);
+}
+
 /* Dump lexical block BLOCK.  BUFFER, SPC and FLAGS are as in
    dump_generic_node.  */
 
@@ -622,6 +695,9 @@ dump_generic_node (pretty_printer *buffer, tree no
   if ((flags & TDF_LINENO) && EXPR_HAS_LOCATION (node))
     dump_location (buffer, EXPR_LOCATION (node));
 
+  if ((flags & TDF_PMU) && pmu_data_present () && EXPR_HAS_LOCATION (node))
+    dump_pmu (buffer, EXPR_LOCATION (node));
+
   switch (TREE_CODE (node))
     {
     case ERROR_MARK:
Index: tree-pretty-print.h
===================================================================
--- tree-pretty-print.h	(revision 191138)
+++ tree-pretty-print.h	(working copy)
@@ -45,6 +45,7 @@ extern void print_generic_expr (FILE *, tree, int)
 extern void print_generic_decl (FILE *, tree, int);
 extern void debug_c_tree (tree);
 extern void dump_omp_clauses (pretty_printer *, tree, int, int);
+extern void dump_pmu (pretty_printer *, location_t);
 extern void print_call_name (pretty_printer *, tree, int);
 extern void debug_generic_expr (tree);
 extern void debug_generic_stmt (tree);
Index: tree-pass.h
===================================================================
--- tree-pass.h	(revision 191138)
+++ tree-pass.h	(working copy)
@@ -84,6 +84,7 @@ enum tree_dump_index
 #define TDF_ENUMERATE_LOCALS (1 << 22)	/* Enumerate locals by uid.  */
 #define TDF_CSELIB	(1 << 23)	/* Dump cselib details.  */
 #define TDF_SCEV	(1 << 24)	/* Dump SCEV details.  */
+#define TDF_PMU         (1 << 25)       /* Dump PMU Profiling details  */
 
 
 /* In tree-dump.c */
Index: gcov.c
===================================================================
--- gcov.c	(revision 191138)
+++ gcov.c	(working copy)
@@ -3022,9 +3022,9 @@ static void process_pmu_profile (void)
         {
           gcov_pmu_st_entry_t *st_entry = XCNEW (gcov_pmu_st_entry_t);
           gcov_read_pmu_string_table_entry (st_entry, length);
+          string_table->st_count++;
           /* Verify that we read string table entries in the right order */
           gcc_assert (st_entry->index == string_table->st_count);
-          string_table->st_count++;
           if (string_table->st_count >= string_table->alloc_st_count)
             {
               string_table->alloc_st_count *= 2;
Index: opts.c
===================================================================
--- opts.c	(revision 191138)
+++ opts.c	(working copy)
@@ -1645,6 +1645,12 @@ common_handle_option (struct gcc_options *opts,
 	opts->x_flag_gcse_after_reload = value;
       break;
 
+    case OPT_fpmu_profile_use_:
+      opts->x_pmu_profile_data = xstrdup (arg);
+      opts->x_flag_pmu_profile_use = true;
+      value = true;
+      break;
+
     case OPT_fprofile_generate_:
       opts->x_profile_data_prefix = xstrdup (arg);
       value = true;
Index: gimple-pretty-print.c
===================================================================
--- gimple-pretty-print.c	(revision 191138)
+++ gimple-pretty-print.c	(working copy)
@@ -26,8 +26,10 @@ along with GCC; see the file COPYING3.  If not see
 #include "tm.h"
 #include "tree.h"
 #include "diagnostic.h"
+#include "basic-block.h"
 #include "tree-pretty-print.h"
 #include "gimple-pretty-print.h"
+#include "coverage.h"
 #include "hashtab.h"
 #include "tree-flow.h"
 #include "tree-pass.h"
@@ -1629,6 +1631,10 @@ dump_gimple_phi (pretty_printer *buffer, gimple ph
 	  pp_decimal_int (buffer, xloc.column);
 	  pp_string (buffer, "] ");
 	}
+      if ((flags & TDF_PMU) && pmu_data_present ()
+          && (gimple_phi_arg_location (phi, i)))
+        dump_pmu (buffer, gimple_phi_arg_location (phi, i));
+
       dump_generic_node (buffer, gimple_phi_arg_def (phi, i), spc, flags,
 			 false);
       pp_character (buffer, '(');
@@ -1875,6 +1881,9 @@ dump_gimple_stmt (pretty_printer *buffer, gimple g
       pp_string (buffer, "] ");
     }
 
+  if ((flags & TDF_PMU) && pmu_data_present () && gimple_has_location (gs))
+    dump_pmu (buffer, gimple_location (gs));
+
   if (flags & TDF_EH)
     {
       int lp_nr = lookup_stmt_eh_lp (gs);
Index: coverage.c
===================================================================
--- coverage.c	(revision 191138)
+++ coverage.c	(working copy)
@@ -96,6 +96,17 @@ typedef struct counts_entry
   struct gcov_ctr_summary summary;
 } counts_entry_t;
 
+typedef struct pmu_entry
+{
+  /* We hash by  */
+  gcov_unsigned_t lineno;
+  char *filename;
+
+  /* Store  */
+  gcov_pmu_ll_info_t *ll_info;
+  gcov_pmu_brm_info_t *brm_info;
+} pmu_entry_t;
+
 static GTY(()) struct coverage_data *functions_head = 0;
 static struct coverage_data **functions_tail = &functions_head;
 static unsigned no_coverage = 0;
@@ -129,6 +140,9 @@ static char pmu_profile_filename[] = "pmuprofile";
 /* Hash table of count data.  */
 static htab_t counts_hash = NULL;
 
+/* Hash table of pmu data, */
+static htab_t pmu_hash = NULL;
+
 /* The names of merge functions for counters.  */
 static const char *const ctr_merge_functions[GCOV_COUNTERS] = GCOV_MERGE_FUNCTIONS;
 static const char *const ctr_names[GCOV_COUNTERS] = GCOV_COUNTER_NAMES;
@@ -159,11 +173,27 @@ static tree gcov_pmu_top_n_address_decl = NULL_TRE
 /* To ensure that the above variables are initialized only once.  */
 static int pmu_profiling_initialized = 0;
 
+/* Cumulative pmu data */
+struct gcov_pmu_summary
+{
+  ll_infos_t ll_infos;         /* load latency infos. */
+  brm_infos_t brm_infos;       /* branch misprediction infos */
+  string_table_t string_table; /* string table entries */
+};
+
+struct gcov_pmu_summary pmu_global_summary;
+
 /* Forward declarations.  */
 static hashval_t htab_counts_entry_hash (const void *);
+static hashval_t htab_pmu_entry_hash (const void *);
 static int htab_counts_entry_eq (const void *, const void *);
+static int htab_pmu_entry_eq (const void *, const void *);
 static void htab_counts_entry_del (void *);
+static void htab_pmu_entry_del (void *);
 static void read_counts_file (const char *, unsigned);
+static void read_pmu_file (const char*);
+static pmu_entry_t *get_pmu_hash_entry (gcov_unsigned_t, gcov_unsigned_t);
+static void process_pmu_data (void);
 static tree build_var (tree, tree, int);
 static void build_fn_info_type (tree, unsigned, tree);
 static void build_info_type (tree, tree);
@@ -211,6 +241,14 @@ htab_counts_entry_hash (const void *of)
   return entry->ident * GCOV_COUNTERS + entry->ctr;
 }
 
+static hashval_t
+htab_pmu_entry_hash (const void *of)
+{
+  const pmu_entry_t *const entry = (const pmu_entry_t *) of;
+
+  return htab_hash_string (entry->filename) + entry->lineno;
+}
+
 static int
 htab_counts_entry_eq (const void *of1, const void *of2)
 {
@@ -220,6 +258,16 @@ htab_counts_entry_eq (const void *of1, const void
   return entry1->ident == entry2->ident && entry1->ctr == entry2->ctr;
 }
 
+static int
+htab_pmu_entry_eq (const void *of1, const void *of2)
+{
+  const pmu_entry_t *const entry1 = (const pmu_entry_t *) of1;
+  const pmu_entry_t *const entry2 = (const pmu_entry_t *) of2;
+
+  return strcmp (entry1->filename, entry2->filename) == 0 &&
+      entry1->lineno == entry2->lineno;
+}
+
 static void
 htab_counts_entry_del (void *of)
 {
@@ -233,6 +281,17 @@ htab_counts_entry_del (void *of)
     }
 }
 
+static void
+htab_pmu_entry_del (void *of)
+{
+  pmu_entry_t *const entry = (pmu_entry_t *) of;
+
+  free (entry->filename);
+  free (entry->ll_info);
+  free (entry->brm_info);
+  free (entry);
+}
+
 /* Returns true if MOD_ID is the id of the last source module.  */
 
 int
@@ -722,6 +781,252 @@ read_counts_file (const char *da_file_name, unsign
   gcov_close ();
 }
 
+/* Read in the pmu profiling file, if available. DA_FILE_NAME is the
+   name of the gcda file. */
+
+static void
+read_pmu_file (const char* da_file_name)
+{
+  gcov_unsigned_t tag;
+  ll_infos_t *ll_infos = &pmu_global_summary.ll_infos;
+  brm_infos_t *brm_infos = &pmu_global_summary.brm_infos;
+  string_table_t *string_table = &pmu_global_summary.string_table;
+  int is_error = 0;
+
+  if (!gcov_open (da_file_name, 1))
+    {
+      if (PARAM_VALUE (PARAM_GCOV_DEBUG))
+        {
+          /* Try to find .gcda file in the current working dir.  */
+          da_file_name = lbasename (da_file_name);
+          if (!gcov_open (da_file_name, 1))
+            return;
+        }
+      else
+        return;
+    }
+
+  if (!gcov_magic (gcov_read_unsigned (), GCOV_DATA_MAGIC))
+    {
+      warning (0, "%qs is not a gcov data file", da_file_name);
+      gcov_close ();
+      return;
+    }
+  else if ((tag = gcov_read_unsigned ()) != GCOV_VERSION)
+    {
+      char v[4], e[4];
+
+      GCOV_UNSIGNED2STRING (v, tag);
+      GCOV_UNSIGNED2STRING (e, GCOV_VERSION);
+
+      warning (0, "%qs is version %q.*s, expected version %q.*s",
+               da_file_name, 4, v, 4, e);
+      gcov_close ();
+      return;
+    }
+
+  /* Read and discard the version. */
+  tag = gcov_read_unsigned ();
+
+  /* Read and discard the stamp.  */
+  tag = gcov_read_unsigned ();
+
+  /* Initialize PMU data fields. */
+  ll_infos->ll_count = 0;
+  ll_infos->alloc_ll_count = 64;
+  ll_infos->ll_array = XCNEWVEC (gcov_pmu_ll_info_t *, ll_infos->alloc_ll_count);
+
+  brm_infos->brm_count = 0;
+  brm_infos->alloc_brm_count = 64;
+  brm_infos->brm_array = XCNEWVEC (gcov_pmu_brm_info_t *,
+                                   brm_infos->alloc_brm_count);
+
+  string_table->st_count = 0;
+  string_table->alloc_st_count = 64;
+  string_table->st_array = XCNEWVEC (gcov_pmu_st_entry_t *,
+                                     string_table->alloc_st_count);
+
+  while ((tag = gcov_read_unsigned ()))
+    {
+      gcov_unsigned_t length = gcov_read_unsigned ();
+      gcov_position_t base = gcov_position ();
+
+      if (tag == GCOV_TAG_PMU_LOAD_LATENCY_INFO)
+        {
+          gcov_pmu_ll_info_t *ll_info = XCNEW (gcov_pmu_ll_info_t);
+          gcov_read_pmu_load_latency_info (ll_info, length);
+          ll_infos->ll_count++;
+          if (ll_infos->ll_count >= ll_infos->alloc_ll_count)
+            {
+              /* need to realloc */
+              ll_infos->ll_array = (gcov_pmu_ll_info_t **)
+                xrealloc (ll_infos->ll_array, 2 * ll_infos->alloc_ll_count);
+            }
+          ll_infos->ll_array[ll_infos->ll_count - 1] = ll_info;
+        }
+      else if (tag == GCOV_TAG_PMU_BRANCH_MISPREDICT_INFO)
+        {
+          gcov_pmu_brm_info_t *brm_info = XCNEW (gcov_pmu_brm_info_t);
+          gcov_read_pmu_branch_mispredict_info (brm_info, length);
+          brm_infos->brm_count++;
+          if (brm_infos->brm_count >= brm_infos->alloc_brm_count)
+            {
+              /* need to realloc */
+              brm_infos->brm_array = (gcov_pmu_brm_info_t **)
+                xrealloc (brm_infos->brm_array, 2 * brm_infos->alloc_brm_count);
+            }
+          brm_infos->brm_array[brm_infos->brm_count - 1] = brm_info;
+        }
+      else if (tag == GCOV_TAG_PMU_TOOL_HEADER)
+        {
+          gcov_pmu_tool_header_t *tool_header = XCNEW (gcov_pmu_tool_header_t);
+          gcov_read_pmu_tool_header (tool_header, length);
+          ll_infos->pmu_tool_header = tool_header;
+          brm_infos->pmu_tool_header = tool_header;
+        }
+      else if (tag == GCOV_TAG_PMU_STRING_TABLE_ENTRY)
+       {
+         gcov_pmu_st_entry_t *st_entry = XCNEW (gcov_pmu_st_entry_t);
+         gcov_read_pmu_string_table_entry (st_entry, length);
+         string_table->st_count++;
+         if (string_table->st_count >= string_table->alloc_st_count)
+           {
+             string_table->alloc_st_count *= 2;
+             string_table->st_array = (gcov_pmu_st_entry_t **)
+                 xrealloc (string_table->st_array,
+                           string_table->alloc_st_count);
+           }
+
+         string_table->st_array[string_table->st_count - 1] = st_entry;
+       }
+
+      gcov_sync (base, length);
+      if ((is_error = gcov_is_error ()))
+       {
+         error (is_error < 0 ? "%qs has overflowed" : "%qs is corrupted",
+                da_file_name);
+          gcov_close ();
+         break;
+       }
+    }
+
+  gcov_close ();
+
+  /* Store pmu data in a global hash table keyed by source position.  */
+  process_pmu_data ();
+}
+
+/* Return a pmu hash table entry for the given FILETAG and LINE, creating
+   a new entry if necessary.  */
+
+static pmu_entry_t *
+get_pmu_hash_entry (gcov_unsigned_t filetag, gcov_unsigned_t line)
+{
+  string_table_t *string_table = &pmu_global_summary.string_table;
+  gcov_pmu_st_entry_t *st_entry;
+  pmu_entry_t **slot, *entry, elt;
+
+  st_entry = string_table->st_array[filetag - 1];
+  elt.lineno = line;
+  elt.filename = xstrdup (st_entry->str);
+  slot = (pmu_entry_t **) htab_find_slot
+      (pmu_hash, &elt, INSERT);
+  entry = *slot;
+  XDELETE (elt.filename);
+  if (!entry)
+    {
+      *slot = entry = XCNEW (pmu_entry_t);
+      entry->lineno = elt.lineno;
+      entry->filename = xstrdup (st_entry->str);
+    }
+  return entry;
+}
+
+/* Process the pmu profiling data, storing it in a global hash table
+   keyed by source position.  */
+
+static void
+process_pmu_data (void)
+{
+  ll_infos_t *ll_infos = &pmu_global_summary.ll_infos;
+  brm_infos_t *brm_infos = &pmu_global_summary.brm_infos;
+  unsigned i;
+  pmu_entry_t *entry;
+  gcov_pmu_ll_info_t *ll_info;
+  gcov_pmu_brm_info_t *brm_info;
+
+  /* Construct hash table with information from gcda file. Entry keys are a
+     unique combination of the filename and the line number for easy access */
+  if (!pmu_hash)
+    pmu_hash = htab_create (10,
+                            htab_pmu_entry_hash, htab_pmu_entry_eq,
+                            htab_pmu_entry_del);
+
+  gcc_assert (pmu_hash != NULL);
+  gcc_assert (ll_infos->ll_count > 0);
+  gcc_assert (brm_infos->brm_count > 0);
+
+  for (i = 0; i < ll_infos->ll_count; ++i)
+    {
+      ll_info = ll_infos->ll_array[i];
+      entry = get_pmu_hash_entry (ll_info->filetag, ll_info->line);
+      entry->ll_info = ll_info;
+    }
+
+  for (i = 0; i < brm_infos->brm_count; ++i)
+    {
+      brm_info = brm_infos->brm_array[i];
+      entry = get_pmu_hash_entry (brm_info->filetag, brm_info->line);
+      entry->brm_info = brm_info;
+    }
+}
+
+/* Returns the load latency info for line number LINENO of source file
+   FILENAME. */
+
+gcov_pmu_ll_info_t *
+get_coverage_pmu_latency (const char* filename, gcov_unsigned_t lineno)
+{
+  pmu_entry_t *entry, elt;
+
+  /* No hash table, no pmu data */
+  if (pmu_hash == NULL)
+    return NULL;
+
+  elt.filename = xstrdup (filename);
+  elt.lineno = lineno;
+
+  entry = (pmu_entry_t *) htab_find (pmu_hash, &elt);
+  XDELETE (elt.filename);
+  if (entry)
+    return entry->ll_info;
+
+  return NULL;
+}
+
+/* Returns the branch misprediction info for line number LINENO of source file
+   FILENAME. */
+
+gcov_pmu_brm_info_t *
+get_coverage_pmu_branch_mispredict (const char* filename, gcov_unsigned_t lineno)
+{
+  pmu_entry_t *entry, elt;
+
+  /* No hash table, no pmu data */
+  if (pmu_hash == NULL)
+    return NULL;
+
+  elt.filename = xstrdup (filename);
+  elt.lineno = lineno;
+
+  entry = (pmu_entry_t *) htab_find (pmu_hash, &elt);
+  XDELETE (elt.filename);
+  if (entry)
+    return entry->brm_info;
+
+  return NULL;
+}
+
 /* Returns the coverage data entry for counter type COUNTER of function
    FUNC. EXPECTED is the number of expected counter entries.  */
 
@@ -1125,6 +1430,14 @@ coverage_function_present (unsigned fn_ident)
   return item != NULL;
 }
 
+/* True if there is PMU data present in this compilation */
+
+bool
+pmu_data_present (void)
+{
+  return (pmu_hash != NULL);
+}
+
 /* Update function and program direct-call coverage counts.  */
 
 void
@@ -2271,6 +2584,11 @@ coverage_init (const char *filename, const char* s
   if (flag_branch_probabilities)
     read_counts_file (da_file_name, 0);
 
+  /* Reads at most one auxiliary GCDA file since we don't support merging */
+  if (flag_pmu_profile_use)
+    read_pmu_file (pmu_profile_data ? pmu_profile_data
+                   : get_da_file_name (pmu_profile_filename));
+
   /* Rebuild counts_hash and read the auxiliary GCDA files.  */
   if (flag_profile_use && L_IPO_COMP_MODE)
     {
Index: coverage.h
===================================================================
--- coverage.h	(revision 191138)
+++ coverage.h	(working copy)
@@ -45,7 +45,12 @@ extern int coverage_counter_alloc (unsigned /*coun
 extern tree tree_coverage_counter_ref (unsigned /*counter*/, unsigned/*num*/);
 /* Use a counter address from the most recent allocation.  */
 extern tree tree_coverage_counter_addr (unsigned /*counter*/, unsigned/*num*/);
-
+/* Get the load latency info for the current file and line */
+extern gcov_pmu_ll_info_t *get_coverage_pmu_latency (const char*,
+                                                     gcov_unsigned_t);
+/* Get the load latency info for the current file and line */
+extern gcov_pmu_brm_info_t *
+get_coverage_pmu_branch_mispredict (const char*, gcov_unsigned_t);
 /* Get all the counters for the current function.  */
 extern gcov_type *get_coverage_counts (unsigned /*counter*/,
 				       unsigned /*expected*/,
@@ -70,6 +75,9 @@ extern void coverage_dc_end_function (void);
    is present in the coverage internal data structures.  */
 extern bool coverage_function_present (unsigned fn_ident);
 
+/* True if there is PMU data present in this compilation. */
+extern bool pmu_data_present (void);
+
 extern tree get_gcov_type (void);
 extern tree get_gcov_unsigned_t (void);
 
Index: common.opt
===================================================================
--- common.opt	(revision 191138)
+++ common.opt	(working copy)
@@ -1683,9 +1683,13 @@ fpmu-profile-generate=
 Common Joined RejectNegative Var(flag_pmu_profile_generate)
 -fpmu-profile-generate=[load-latency]  Generate pmu profile for cache misses. Currently only pfmon based load latency profiling is supported on Intel/PEBS and AMD/IBS platforms.
 
+fpmu-profile-use
+Common Var(flag_pmu_profile_use)
+-fpmu-profile-use=[pmuprofile.gcda]  The pmu profile data file to use for pmu feedback.
+
 fpmu-profile-use=
-Common Joined RejectNegative Var(flag_pmu_profile_use)
--fpmu-profile-use=[load-latency]  Use pmu profile data while optimizing.  Currently only perfmon based load latency profiling is supported on Intel/PEBS and AMD/IBS platforms.
+Common Joined RejectNegative Var(pmu_profile_data)
+-fpmu-profile-use=[pmuprofile.gcda]  The pmu profile data file to use for pmu feedback.
 
 fpredictive-commoning
 Common Report Var(flag_predictive_commoning) Optimization

--
This patch is available for review at http://codereview.appspot.com/6551072